Stompy back on top in Pauper

After the banning of Peregrine Drake, people expected midrange decks such as Murasa Tron and MBC to rise to the top again.

Curiously this has not been the case.

This is the metagame today

1. Stompy 12.5% (29 decks)
2. Delver 12.07% (28 decks)
3. Affinity 12.07% (28 decks)
4. Kuldotha Boros 9.05% (21 decks)
5. Elves 6.47% (15 decks)

Five aggro decks! MBC is nowhere to be seen. Tron is at #6.

Why? I believe the metagame is still in flux and that perhaps people are just picking midrange decks that are too slow. For now Pauper seems to be an aggrofest. If you want to play more than one color you better make it Affinity or Boros.

Here is a sample 5-0 Stompy deck. Some choice suprise me. Wild Mongrel and Basking Rootwalla are tested and found to be wanting long ago in the Stompy lists. I don't see what makes them viable now.

Main Deck
2 Basking Rootwalla
1 Bonesplitter
1 Epic Confrontation
16 Forest
2 Garruk's Companion
4 Groundswell
2 Mutagenic Growth
4 Nettle Sentinel
4 Quirion Ranger
4 Rancor
2 River Boa
2 Silhana Ledgewalker
4 Skarrgan Pit-Skulk
2 Vault Skirge
4 Vines of Vastwood
2 Wild Mongrel
4 Young Wolf

Sideboard
3 Epic Confrontation
4 Gleeful Sabotage
2 Gut Shot
2 Natural State
1 Relic of Progenitus
3 Scattershot Archer

Do you have any thoughts on why aggro is dominating a format supposed to be dominated by midrange? How did Drake deal with all this aggression so successfully? Or did it?